This proposal is for support of research under the Foundation's Presidential Young Investigator (PYI) Awards program. Dr. Stein's research is directed at design and control of servo systems. The work is divided into six projects. Four of these areas are concerned with machine development for factory automation. The other two areas are concerned with the development of improved prostheses for lower limb amputees. The specific projects are as follows: Control of DC Servo Machine Tool Drive Systems for Machine Diagnostics, Design and Control of Pneumatic Servo Systems for Factory Automation, Expert Systems Applied to Model Based Diagnostics of Servo Systems, Models of Machine Tool Drive Train Components for Machine Diagnostics, Design and Control of Prosthetic Limbs, and Development of Microprocessor Controlled Above-Knee Prostheses Simulator. The objectives of the PYI program are to provide support to the Nation's most outstanding and promising young science and engineering faculty. The awards are intended to improve the capability of U.S. academic institutions to respond to the demand for highly qualified scientists and engineers for academic and industrial research and teaching. In accordance with those objectives, a Presidential Young Investigator Award for Dr. Stein is recommended. This is a five-year continuing award. Annual funding will be at the base level of $25,000 with a supplement of up to $37,500 to match industrial support obtained.